Electric devices and metal wires that constitute the interior of devices such as organic or inorganic light-emitting device, display devices, and photovoltaic devices, when brought into contact with external chemical materials such as oxygen and moisture, tend to deteriorate or get oxidized, and become unable to perform their designated functions. Therefore, there is a need to protect the electric components from such chemical materials. To this end, the use of a glass plate as a substrate material or cover plate has been proposed as a means to insulate the chemical-sensitive internal devices. Glass plates have the advantages that they are adequate in terms of light transmittance, thermal expansion coefficient and chemical resistance. However, glass has the disadvantage that it is not only heavy but also brittle and fragile, requiring much caution in handling.
Accordingly, there are active attempts to replace glass plates with plastic, which is a material being lighter and having higher shock resistance and more flexibility than the glass plate currently in use for electronic devices. However, plastic films that are commercially manufactured at the present time have many disadvantages in terms of physical properties compared to the glass plates, requiring improvements therein. In particular, improvements are urgently needed in water resistance and a gas barrier property of plastic, and research has been actively conducted worldwide to develop a barrier film that uses a plastic film. Further, in view of possible applications that utilize light, such as in display or photovoltaic devices, a barrier film is required to possess not only an excellent gas barrier property but also excellent light transmittance. For a barrier film to be utilized in information-conveying display applications, not only is excellent light transmittance important, but its yellowness index is also important. If barrier films used in display manufacture have too high an absolute value of the yellowness index, distortion in the color aspect of optical data displayed on the device can be caused. Therefore, a barrier film having both an excellent gas barrier property and light transmittance is required.